A great many different types of machines are powered primarily or in part with electric drive systems. Examples include electrically propelled land and water vehicles, industrial equipment, elevators, and many others. Like all mechanical and electromechanical systems extremes of temperature during operation and/or thermal fatigue over time can occur in electric drives, leading to performance degradation or failure. Direct observation of temperature can be challenging or impossible particularly when an electric drive system is in service in the field. The industry is therefore welcoming of advances in relation to temperature measurement or estimation.